Urinary Tract (Ch 27) Flashcards
What is included in the urinary tract?
- ureters
- bladder
- urethra
- -> NOT kidneys
Ureter
- -> how urine exits the body
- fibromuscular tubes located peritoneally
- ureters go from kidney inferiorly to bladder
- urine transported by gravity/peristaltic waves (smooth musc in ureter wall)
Kidney Stones
a.k.a. “renal calculus”
when minerals filtering through the kidneys accumulate = crystals
-80% in men
How do you identify kidney stones?
Location: kidney, ureter, bladder
Type: calcium, struvite, uric acid
What causes kidney stones?
- dehydration
- abnormal pH of urine
- over saturation of calcium/uric acid/oxialate
- block of urine flow
- bacterial infection
Urinary Bladder
muscular sac that stores/expels urine
- holds up to 1 liter of urine (stretches as it fills)
- lies on pelvic floor posterior to pubic symphysis
What is the mucosa of the urinary bladder composed of?
transitional epithelium + lamina propria
-has rugae (“folds”) that will expand
what is the function of the detrusor muscle in the urinary bladder?
contracts/squeezes urine from bladder
Urethra
tube lined with smooth muscle + mucosa
- -> drains urine from bladder
- longer in males (composed of prostatic, intermediate, and spongy urethra)
internal urethral sphincter
created by the thickening of the detrusor muscle
- at the bladder/urethra junction
- relaxation INVOLUNTARY
external urethral sphincter
surrounds urethra w/skeletal muscle sheet
–> inhibits urine
Females: close to outside of body, males: at base of penis
*potty training = learning to control
*relaxation VOLUNTARY
Micturition
- urination
- controlled by brain (pons) –> when bladder is distended (full) stretch receptors send signals to pons –> detrusor muscle stimulated to squeeze out urine
What are the functions of the urinary system?
- eliminate nitrogenous wastes + excess ions (storage/excretion of urine)
- maintain ion balance, acid-base balance, regulates blood volume
Kidney Anatomy
- bean shaped structure
- located in retroperitoneal position
- protected by floating ribs
- filters blood
Structures of the kidney
renal cortex renal medulla renal pyramid (in renal medulla) renal pelvis renal column ureter fibrous capsule papilla of pyramid minor/major calyx hilium
Kidney Blood Supply
- renal arteries branch
- travel through renal columns
- reach afferent arterioles
- -> form capillary network (glomerulus) - once blood is filtered…exits through efferent arteriole
- branch into peritubular capillaries surrounding nephron structures
- drain into interlobar vessels
Vasa Recta
peritubular capillaries around Loop of Henle
peritubular capillaries
- kidney
- adapted to absorb materials not retained in filtrate (becoming urine)
The nephron
- smallest functional unit of kidney
- site of filtration of water from blood (filtrate –> urine)
- millions of nephrons in each renal pyramid
What are the two types of nephrons?
- Cortical (85%): mostly located in cortex
2. Juxtamedullary (15%) –> very long loops, help concentrate urine
What are the two main parts of nephrons?
- Renal Corpuscle
2. Renal Tubules
Renal Corpuscle
glomerulus + glomerular (“bowmans”) capsule
- capillary bed
- afferent arterioles bring blood in
- glomerular capsule captures filtrate pushed out of capillaries
How do blood and filtrate enter/exit the nephron?
blood: enters via afferent arteriole, exits via effferent arteriole
filtrate: enters via afferent arteriole, leaks out glomerulus, exits via proximal convoluted tubule
What is filtrate?
water, waste, salt, glucose
Structure of Renal Tubules
filtrate --> tubules (via renal corpuscle) Include: -Proximal Convoluted Tubule -Loop of Henle -Distal Convoluted Tubule -Collecting Duct
Renal Tubules: Proximal Convoluted Tubule
- made of cuboid epithelial cells
- secretory/absorptive (reabsorbs solutes/nutrients)
Renal Tubules: Loop of Henle
- descending limb permeable: simple squamous epithelium
- ascending limb permeable to water (reabsorb water)
Renal Tubules: Distal Convoluted Tubule
- made of cuboid epithelial cells
- selectively secretory/absorptive (secretes ions)
- -> exits into collecting ducts
Three steps of urine formation
- Glomerular Filtration
- Tubular Reabsorption
- Tubular Secretion
Glomerular Filtration
- in glomerulus
1. blood is filtered into filtrate (water and wastes)
2. exit out of renal corpuscle into PCT - -> movement of substances from the blood within the glomerulus into capsular space
Tubular Reabsorption
- in PCT and Loop of Henle (Nephron Loop)
- ->movement of substances from the tubular fluid back into the blood, absorption of ions and water
Tubular Secretion
*in DCT
secretion of potassium and hydrogen
–> movement of substances from blood into tubular fluid
renal column
divide kidney up into portions (renal pyramids)
flow through kidney
renal column–>renal pyramid–>renal papilla–>minor calyx–> major calyx –> renal pelvis –> ureter
Hilum
indentation on kidney where renal artery, renal vein, and ureter enter/exit the kidney
